In-line roller skates have become very popular with the public in the past few years. However, the in-line roller skates that are available on the market have a number of inherent limitations. For one thing, the wheels and axles are rigidly mounted to the frame member under the boot and there is minimal shock absorbing capacity built into the wheels. Accordingly, it is difficult for a person wearing conventional in-line roller skates to skate over uneven or bumpy surfaces. This is particularly important during long downhill runs at high speeds. Transmission of excessive high frequency low amplitude vibration due to road surface irregularities may blister a skaters foot as well as cause fatigue. Impacts of high amplitude at any frequency may cause a loss of balance and a serious fall.
Existing in-line skates offer limited shock absorption through the use of a slightly soft tire compound which compensates for only minor bumps. Such tires require frequent replacement due to wear and tear. Use of a relatively soft tire compound, while lending more shock absorbing capacity, increases rolling friction and detrimental heat buildup. This may soften the tire, degrade bearings and overall, require greater skating effort, particularly in high ambient temperatures.
Existing in-line skates usually have three to five tandem wheels in relatively rigid horizontal and vertical alignment. In a three wheel skate, when a skater encounters a bump, in forward motion, the initial upward wheel impact forces the toe upward. Impact with the following middle wheel raises the toe still further leaving ground contact substantially with the final wheel. This action tends to destabilize the skater by removing toe contact which normally supplies the best control.
Allowing independent wheel deflection vertically while maintaining lateral rigidity would enable greater control and stability over relatively rough terrain. Transferring the resilient action away from the tire also would allow the use of harder tire compounds
Another problem is braking. Most in-line skates have a rear brake pad on one skate. It would be helpful if a wheel rotation stopping mechanism could be used. This would avoid unwanted wheel rotation.
U.S. Pat. No. 4,915,399, Merandel, granted Apr. 10, 1990 discloses a front and rear wheel roller skate design which has a suspension system on the front and rear wheels. The roller skate is equipped at the level of the front and rear pivoting axles, with a suspension system for damping shocks resulting from unevenness of a skating surface. The front and rear pivoting axles are each provided with a suspension system which is fixed at one end on the central part of the pivoting axle, and at the other end being guided by a centring barrel located inside a base of the skate. The pivoting axles are also each equipped with a pivoting system secured at one end to the base by a pivoting device while the other end is secured to an arm of the central part by resilient washers. Marandel does not disclose in-line roller skates. He discloses conventional roller skates with a pair of wheels on a front axle and a pair of wheels on a rear axle.
U.S. Pat. No. 5,092,614, Malewicz, assigned to Rollerblade, Inc., granted Mar. 3, 1992, discloses a lightweight in-line roller skate frame and frame mounting system. The in-line roller skate has a frame including a pair of side rails, each side rail having front and rear mounting brackets for attachment of the frame to the boot of the in-line roller skate. Each frame side rail includes a curved portion and a planar portion. The planar portion carries a plurality of axle apertures through which an axle for a wheel may be inserted. Preferably, the axle apertures are configured to receive an axle aperture plug, have an eccentrically disposed axle bore and are situated on the frame side rails such that the wheels may be mounted at multiple relative heights to each other. Malewicz does not disclose any shock absorbing mechanism for the in-line wheels, or any ability for the wheels to move upwardly or downwardly in order to recede when the wheels impact a bump or obstruction.